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Cave secrets

Dr Douka and colleagues discuss findings at the Denisova Cave in Russia that cast new light on early human migration patternsZelensky/Sab-Russian Academy of Science

12Jan
2018

Instead of gradually leaving Africa in a single wave, new fossil discoveries are showing that early humans left the continent in multiple waves, across many tens of thousands of years

The spread of humanity through the ‘Out of Africa’ theory has been common knowledge for several decades. Yet new discoveries continue to tweak and evolve the narrative. New research on fossils retrieved from across China and Southeast Asia backs up a more recent idea that, instead of a single wave of migration around 60,000 years ago that carried our ancestors into Asia and then around the world, there were multiple waves of migration, dating back as long ago as 120,000 years (and quite potentially earlier), with instances of interbreeding often occurring along the way.

‘By bringing together all current evidence from archaeology, genetics and fossil finds, we demonstrate that, while post-60,000 years ago expansions certainly happened and greatly influenced the world as we know it today, this was not a simple, single and rapid expansion as one wave of movement, but a much more complicated situation,’ outlines Dr Katerina Douka, researcher in archaeological science at the Max Planck Institute for the Science of Human History in Jena, Germany. ‘This was certainly not one early wave but multiple exits through time. Small hunting and gathering groups, moving in a piecemeal fashion, in different parts of Eurasia. Most of these lineages became locally extinct leaving no DNA trace in current peoples.’

Douka and her colleagues focused their most recent work on various sites across Asia, trying to fill in gaps in a region of the world that has been neglected when compared to well-studied sites in Europe and Africa. ‘Things have changed recently and there are a few, modern interdisciplinary projects in Asia that provide important new insights,’ she explains. ‘From the fieldwork in Arabia of Mike Petraglia and his team, to our work in Siberia, to Christopher Bae’s work in China and Korea, as well as the many Australian teams working in Southeast Asia, this is an exciting time – with new discoveries every few weeks.’

This is, of course, not to say that this latest research is fully capable of drawing a line underneath the remaining mysteries of early human migration. As Douka describes, there are still ‘gigantic geographic gaps’ which remain to be filled in across Asia. ‘Hopefully,’ she adds, ‘our publication will help local and international agencies to grasp the importance of undiscovered sites in regions such as Central Asia, in high-altitude cave sites across the continent, as well as in the periphery of what was once Sundaland [an ancient southeast Asian landmass covering what is now the Malay peninsula, Borneo, Sumatra, and much of the South China Sea].’

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